Clinical improvements seen
In the MycarinG study, patients received weekly injections of 7 mg/kg, 10 mg/kg rozanolixizumab, or placebo over a 6-week period. Both treatment groups had reductions in Myasthenia Gravis Activities of Daily Living (MG-ADL) scores compared with placebo.
MG-ADL and Quantitative Myasthenia Gravis (QMG) scores were consistent across treatment cycles. The mean MG-ADL score dropped by about 4 points at week 6. At around week 10, the mean improvement declined to 2 points, and then by week 14 it increased to 3 points, where it remained consistent out to 50 weeks. A similar pattern was seen in QMG scores, with an approximate 5-point drop at 6 weeks, then about a 1.5-point improvement at 10 weeks, then a mean decrease of around 4 points that stayed stable out to 50 weeks.
Over all cycles of treatment, 89.9% of patients experienced a treatment-emergent adverse event, including 22.3% who had a serious TEAE; the study dropout rate because of TEAEs was 15.4%.
In the ADAPT-SC study, 110 patients were randomized to 10 mg/kg intravenous efgartigimod or 1,000 mg efgartigimod PH20, which is formulated with recombinant human hyaluronidase to allow for rapid administration of larger volumes. After completion of ADAPT-SC, 105 patients from both groups and an additional 79 patients entered the open-label extension study with 1,000 mg efgartigimod PH20.
The study included 141 patients who were AChR-Ab positive and 38 who were AChR-Ab negative. In the first cycle, 34.6% experienced an injection-site reaction, which steadily dropped to 11.5% by the sixth cycle. After each cycle of treatment, the mean change in MG-ADL from study baseline at week 4 was between 4.1 and 4.7 points. The mean change in Myasthenia Gravis Quality of Life 15-Item Questionnaire revisited from study baseline at week 4 was between 5.1 and 6.5 points. The mean change in EuroQoL 5-dimension, 5-level visual analog scale was between 12.3 and 16.0 points at week 4.
MyCarinG was funded by UCB Pharma. ADAPT-SC was funded by Argenx SE. Dr. Bril has financial relationships with Behring, Argenyx, Alexion, Immunovant, Alnylam, Akcea, Takeda, Sanofi, Ionis, Roche, Novo Nordisk, Octapharma, Momenta, Pfizer, CSL Behring, Grifols, Powell Mansfield, UCB, and Viela Bio. Dr. Small is on the speaker’s bureau for Alexion.